First off, I hope this is the right spot. I consider myself all grain now even though I don't have all the extra equipment.

First batch with BIAB was an IPA that ended up around 55% calculated efficiency. Luckily, I was targeting a little higher gravity so the low efficiency didn't kill me.

Second batch was a Kolsch that I also targeted high. Again, I ended up low, but this time with some mild improvement (60%). Both efficiency numbers were gotten by changing the efficiency number in the brewers friend recipe calculator until my OG matched the program.

A couple of notes about my set-up and process.

10 gallon brew pot, custom bag (fiance sewed it for me) that fits well over the edges.

Grains were sent through the mill at the homebrew store, so even though I have read that grain can be practically pulverized without any fear of tannins due to the mesh of the bag, I had 'regular' crushed grain.

Mashed between 154-150 for the IPA, and 152-146 with the Kolsch. Both were stirred periodically and the temp brought up by boiling water when it dropped. I had three different thermometers (brew pot, probe, and a digital stick) and they all pretty much were around the above temps.

Mashed for 70 mins on the IPA and 80 mins on the Kolsch.

No iodine test because I don't have any.

Small sparge of grains on IPA after I pulled the bag (~2 qts at 170 over spent grains). Kolsch grains sat over a strainer, and I added all the drippings back.

Both batches ended up at the volume I wanted, so I don't think it was an issue of adding too much water.

No pH taken during the whole thing either. No dark malt to bring acidity down, but I don't think my water would lead to higher pH (near Boston, MA).

Sorry for the length, but I wanted to be thorough. What are the top reasons I could of ended up with a low efficiency.

I do not do a BIAB but the times I have done a partigyle the first batch is usually around a 60-65% efficiency in my system. Also, as I go up in gravity my efficiency does go down quite a bit as I do not have a really large boil kettle to collect a lot of sparge and boil it down. I would expect 55-60% to be fairly typical for a higher gravity BIAB.

when i biab-ed, i would mash for at least 90 minutes. i built a "jacket" for the kettle out of 1" foam sheathing from home depot. it held temps pretty well. i never sparged and never worried about ph and still hit about 72-74% every time. i also found i needed to hit higher strike water temps to hit mash temps i wanted on my system.

my first suggestion is to mash longer. the research i did and the results i had show 90 minutes plus for a biab mash is a good thing. second suggestion, mill twice if you can. i did and while it didn't noticeably add points to efficiency, it didn't take them away.

I'm still dialing in my BIAB setup, but my efficiency has been as low as the 60's in brews where my grain wasn't crushed fine/twice and I wasn't squeezing super hard. I've had efficiency as high as 80% on a 1.110 barleywine, but the grains were crushed extra fine and I really made sure to squeeze as much as I could out of the bag.

I'm still dialing in my BIAB setup, but my efficiency has been as low as the 60's in brews where my grain wasn't crushed fine/twice and I wasn't squeezing super hard. I've had efficiency as high as 80% on a 1.110 barleywine, but the grains were crushed extra fine and I really made sure to squeeze as much as I could out of the bag.

I have been doing 2.5 gallon BIAB's now for about 10-15 batches. what erockrph said is what I would recommend. Also If you have a lot of adjuncts in your recipe you wont see as good eff at a 60 min mash.

I usually just do 60 and compensate a little grain if I know I have a lot of adjuncts. IE oats, wheat.

I have only done BIAB in my short brewing career (maybe 20+ BIAB batches) I don't sparge and I am a dead 70% efficiency every time..(It's not great, but not bad either)

I agree with above..

1. Ask your LHBS to run it twice through the mill. Usually it doesn't do much, but if their machine hasn't been calibrated lately, it can make a difference.

2. I always squeeze the bag! And to be honest I've noticed an increase in efficiency from this alone.

3. For what its worth I have a buddy doing all grain (not BIAB) he had gotten horrible efficiency on his last few batches, I brought over some pH strips and sure enough he was way high... Maybe someone else can go into further detail about this.

Efficiency problems usually involve the crush or the volume measurements. Did you get the volume you expected? If not this could have a huge impact on your efficiency calculations. If it is not those two things, then consider a squeeze of the bag or a slight rinse of the grain bag next time.

Logged

Dave

"This is grain, which any fool can eat, but for which the Lord intended a more divine means of consumption. Let us give praise to our Maker, and glory to His bounty, by learning about... BEER!" - Friar Tuck (Robin Hood - Prince of Thieves)

when the weather is stupid hot or cold I move inside and do a sort of BIAB in the kitchen. Didn't like the heat I lost from the brewpot, so used a 5g plain (blue) cooler, and a bag that fit perfectly over the rim. After however long I am mashing I pull the bag out of the cooler (yeah it's heavy but it helps that I make smaller batches) and move to a second smaller brewpot filled with water hot enough to bring to the upper 160's for mash-out. So, sort of a BIAB single batch sparge. Then I add in a strainer and it drains (usually pour the last gallon of water over it) while I'm heating up the first "runnings" from the cooler. My efficiency is lower but nowhere near 55-60%. Generally above 75%. Just did this yesterday with a Dusseldorf Alt rather than go outside in 14F weather, and was at 78%.

I think your top problem is the 2 qt grain rinse. The grain absorbs water, for example - 10 lbs of grain will absorb 2 gallons of water. At the end of the mash, all of the water in the pot should be evenly saturated with sugars - including the water inside the grains. So when you pull out that grain (and the water) you could be pulling out 20% of the sugars too - or more - depending on how much water is in the pot.

How much water are you mashing with?

Logged

Delmarva United Homebrewers - President by inverse coup - former president ousted himself.AHA Member since 2006BJCP Certified: B0958

I agree with dmtaylor and mtnrockhopper on this one. What are your volumes at each step in your process? The crush definitely is/can be the first thing you can correct easily if this concerns you. Not that I have to, but I double crush my grains. It's more about reaching consistent numbers than shooting for a specific number. If I felt all I could get was 60%, with the effort I wanted to give, and I got that every time using a specific method, then I'd be happy and wouldn't worry about chasing 70% or 95% unless my pocketbook or quality was affected.

The way you are calculating efficiency through BrewersFriend suggests you may not be accounting for your final volume, which can be different from what the recipe states. Your volume measurements may swing your efficiency around 5-10% if you aren't careful. Gravity is not the only factor in calculating efficiency.

I agree with dmtaylor and mtnrockhopper on this one. What are your volumes at each step in your process? The crush definitely is/can be the first thing you can correct easily if this concerns you. Not that I have to, but I double crush my grains. It's more about reaching consistent numbers than shooting for a specific number. If I felt all I could get was 60%, with the effort I wanted to give, and I got that every time using a specific method, then I'd be happy and wouldn't worry about chasing 70% or 95% unless my pocketbook or quality was affected.

The way you are calculating efficiency through BrewersFriend suggests you may not be accounting for your final volume, which can be different from what the recipe states. Your volume measurements may swing your efficiency around 5-10% if you aren't careful. Gravity is not the only factor in calculating efficiency.

So to answer some of the questions asked (and not just those in the above post)- I did not double crush. My LHBS lets me crush my own grains, so running it through twice shouldn't be an issue- I did hit final volume on both beers 5.5 gal. I had to actually add a little water on the IPA. - My pre boil volumes: IPA 7.25-7.5 gal (pre-boil, mash was closer to 7); Kolsch 8 gal (mash and pre-boil volumes)- IPA was the one I did a little bit of a sparge.

The most likely culprits to me appears to be crush, squeezing, and maybe pH. After I posted, I also read in another BIAB thread that it was recommended to bring the temp up to 165 or so for about 10 mins. Can anyone explain why this would aid efficiency.

I am not worried about the low efficiency if I can be consistent. What I am worried about is that I start scaling up recipes to compensate, and I end up with some monster out of balance by accident for my 3rd BIAB. I guess I will still just target the upper ABV for the style, and if I net out a little low, it will still be okay.

Luckily, the IPA has dropped to 1.004. The Kolsch is still TBD. I did a Brix and Gravity on the IPA and both seem to converge at around 7% which is what I was targeting. I don't think that sort of attenuation is repeatable though.

I also read in another BIAB thread that it was recommended to bring the temp up to 165 or so for about 10 mins. Can anyone explain why this would aid efficiency.

Allegedly, this could thin out the wort a bit and help it drain from the grain bed more easily when you pull your bag. Personally, I don't know if I buy that. And I'm certainly not going to squeeze a 165F bag of hot grain by hand.

I am not worried about the low efficiency if I can be consistent. What I am worried about is that I start scaling up recipes to compensate, and I end up with some monster out of balance by accident for my 3rd BIAB. I guess I will still just target the upper ABV for the style, and if I net out a little low, it will still be okay.

Just have some DME on hand if you need to boost your gravity in the end.

Luckily, the IPA has dropped to 1.004. The Kolsch is still TBD. I did a Brix and Gravity on the IPA and both seem to converge at around 7% which is what I was targeting. I don't think that sort of attenuation is repeatable though.

That attenuation number has me wondering how you are measuring your gravity. Is your hydrometer's calibration off? That would certainly explain your efficiency issues.

That attenuation number has me wondering how you are measuring your gravity. Is your hydrometer's calibration off? That would certainly explain your efficiency issues.

I thought this too, but I have been brewing extract for awhile and never saw an issue. Obviously something could have happened to it in the past month or so.

How would I check it's calibration. Is there a standard procedure for using sugar water or something to determine if it's on? I used a refractometer for the first time these past two batches, and the numbers seemed align. If someone has a calculator or tool or something that can help me out, I would really appreciate it.

That attenuation number has me wondering how you are measuring your gravity. Is your hydrometer's calibration off? That would certainly explain your efficiency issues.

I thought this too, but I have been brewing extract for awhile and never saw an issue. Obviously something could have happened to it in the past month or so.

How would I check it's calibration. Is there a standard procedure for using sugar water or something to determine if it's on? I used a refractometer for the first time these past two batches, and the numbers seemed align. If someone has a calculator or tool or something that can help me out, I would really appreciate it.

Float your hydrometer in distilled or RO water. It should read 1.000 at it's calibrated temp (usually 68F or 60F).